1. Field of the Invention
The present invention relates to an interstitial marker for localization of organs, tumors and tumor beds using various imaging modalities. More particularly, it relates to an interstitial marker formed of a plurality off concentric rings joined on a inner ribbon.
2. Discussion of Related Art
Interstitial markers have long been known to the medical world. They have been used to prepare patients undergoing radiation treatment whereas such treatments are usually split into daily doses or fractions. The markers help the radiation treat the same area each time treatment is performed on a given patient's tumor. Additional uses of interstitial markers are in the tracking of the location of a suspected tumor during biopsy and the tracking of the volume or the changing volume of a tumor over time either increasing or decreasing in size to gage treatment effectiveness.
Historically markers have been produced of metal “seeds” pre-shaped in the form of a grain of rice or a sphere. Other markers have been in the design of a pre-formed metal coil. Both types of design can have limitations. The solid “seed” type designs have been known to move or migrate from the intended tissue. Movement and/or migration of the marker eliminates the ability to target the intended tissue. The coil design is more stable in tissue and can be viewed under more imaging modalities but it is subject to both compression and elongation, both of which can negate the usefulness of the marker.
In some instances, flexibility of an interstitial marker can be useful for monitoring organs and tumors. For example, a flexible marker may change position and shape as a tumor grows or shrinks. In order to achieve sufficient flexibility, the dimensions of the marker are small. A small marker does not appear as well in the various imaging modalities. Some existing markers have sought to improve the visibility of the marker while maintaining its flexibility though creation of a helical coil from a fine wire. However, such markers can still be difficult to locate due to the small size of the wire. The cross sectional density of the material makes a maker more or less visible than other under most common imaging modalities. Even when using a very dense material, a very small coil will not have a thick enough cross section of material to be visible when imaged. A coil produced from fine wire has an almost smooth texture. This smoothness results in an increase chance of movement in the tissue as well as a surface that is less visible under certain imaging modalities.
Interstitial markers are used to mark locations for visualization under different types of imaging modalities. Materials used to form a marker appear differently under different imaging modalities. Therefore, a marker from a single material may work well with some modalities and not as well for others.